Add support for ProgramDatabaseFile to Ninja
Currently we ignore the ProgramDatabaseFile option in the linker
portion of the GYP file. This change will cause the /PDB:<name>
switch to be emitted during the link step as part of ldflags.
Since ldflags are appended to the defaults, they override any
default /PDB switches that are current emitted which is consistent
with our current uses.
BUG=126499
TEST=gyptest-link-pdb
Committed: https://code.google.com/p/gyp/source/detail?r=1530